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Comment by justnotworthit | Hacker News Reader

> We know from the cruise ship data like the Diamond Princess that most people had no symptoms initially, but overtime most people became symptomatic [1].

Your wording is too strong. Data is 50% asymptomatic at time of testing, paper models that that number dropped to 20%.

> from paper on 19 February and 50.5% (320/634) on 20 February (Table). Soon after identification of the first infections, both symptomatic and asymptomatic cases were transported to designated medical facilities specialised in infectious diseases in Japan. However, these patients were treated as external (imported) cases, and a detailed description of their clinical progression is not publicly available.

We conducted statistical modelling to derive the delay-adjusted asymptomatic proportion of infections, along with the infections’ timeline. The estimated asymptomatic proportion was 17.9% (95% credible interval (CrI): 15.5–20.2%).

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If you read in the discussion they reference other data sets to show that more asymptomatic become symptomatic. It is also what the Icelanders found with their data too where most people started out asymptomatic, but many later developed symptoms.

In a region in Italy they tested [1] people twice, 2 weeks apart, and found that 43% were completely asymptomatic over the course of the infection.

[1] https://www.medrxiv.org/content/10.1101/2020.04.17.20053157v...

Doesn’t that mean that 57% were symptomatic?

I didn't intend to contradict you. Granted it's totally valid to assume that many people who are tested positive and show no symptoms might develop some later, but I just thought it might be of interest to some people to have numbers where they tested patients twice over a long enough interval to conclude that they really were asymptomatic.

About 50% of the population in that study is over 50. I think it's a bad idea to draw generic conclusions about the disease from a diverse age range. You end up with conclusions that aren't relevant to either. Glossing over the tables I don't see any data about symptomatic over the two weeks by age. I'd be shocked if the rates of becoming symptomatic are not much higher for the elderly and much lower for the young. Didn't read it in depth though.

See: Simpson’s paradox, where trends in subgroups, taken together, can indicate a different trend.

https://en.wikipedia.org/wiki/Simpson%27s_paradox

Trends in subgroups can indicate a different trend. The above comment is not about a linear trend. It's about an average statistic for a population based on a sample that's not representative of the population age distribution for a process that probably isn't linear across ages. If the older half becomes symptomatic 100% of the time, and the younger half becomes symptomatic 0% of the time, it's very misleading, though not technically incorrect to say people become symptomatic 50% of the time. There's a huge impact on how to handle the problem.

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